Starting relay for fluorescent lamps



April 1949- H. B. SHAPER ET AL 2,466,053

STARTING RELAY FOR FLUORESCENT LAMPS Filed April 30, 1945 2 Sheets-Sheet l LINE ll VOLTAGE [148 1 FIG. I W I LINE [I ,0 [z VOLTAGE IL ZI 5g i k K l5,

an i I9 2 Q? /54 VIBRATQR I6 55 ll 0 F IQ/IVIBRATOR l7 [8 v INVENTORS HARRY s. SHAPER F BY CLIFFORD v. FRANKS ATTORNEY April 5, 1949.

H. B. SHAPER ETAL 2,466,053

STARTING RELAY FOR FLUORESCENT LAMPS Filed April 30, 1945 2 Shets-Sheet 2 LINE VOLTAGE F'lG..5'

INVENTORS HARRY B. SHAPER CLIFFORD V. FRANKS Patented Apr. 5, 1949 2,466,053 STARTING RELAY FOR FLUORESCENT LAMPS Harry B. Shaper, Cleveland V. Franks, Cleveland, 0111 Heights, and Clifford o, assignors to The Brush Development Company, Cleveland, Ohio,

a corporation of Oh Application April 30, 1945, Serial No. 591,194

' 3 Claims. (Cl. l7l 330) There has long been a need for a circuit and/or device for quickly starting a discharge device such as a fluorescent lamp after its switch is thrown, as one of the biggest drawbacks to fluorescent lamps is the time interval or lag between easier the lamp will start, but heating requires ectionable, and care must be exercised to keep the filaments from getting too hot as excess heating, both as to degree and duration, reduces lamp life.

It is an object of our invention to provide a lamp starting circuit and switch which will provide sufficient heating time and sufiicient voltage in a surge to quickly start a discharge lamp yet which will allow good lamp life.

An object of the invention is to provide a new and improved circuit for starting an electric discharge device.

A further object of the invention is to provide a new and improved switch for use with circuits for starting an electric discharge device.

A further object of the invention is to provide equipment for starting fluorescent lamps which can readily be applied to existing fluorescent lamp installations.

Other objects and a fuller understanding of be had by referring to the following description and drawings wherein:

Figures 1 to 4 are diagrams of circuits for initiating discharge in electric devices, and Figure 5 illustrates a vibratile switch for use in the circuits of Figures 1 to 4.

In Figure 1 there is shown an electric discharge device 10 of the fluorescent tube type having coated filaments or cathodes H, I 2 at its ends, connected through ballast I3 and a condenser H to a source of voltage [5. This voltage source l5 may be line voltage for the smaller size lamps but for the larger sizes a transformer Whose secondary output has a voltage on the order of twice line voltage is desirable. A normally open switch l6 of the manually operated type is provided between the source of line voltage and the transformer l5, and may be closed to light the lamp. Across the lamp electrodes II, I! there is connected a normally open switch l1, and in parallel with the switch there is a circuit including a glow tube l8 and a vibrator I 9.

When it is desired that the lamp I 0 be lit the switch I6 is closed, applying line voltage to the transformer The transformer generates a voltage in the neighborhood of 200 to 250 volts. At this voltage the glow tube I8 is conducting making a circuit through the inductor l3, condenser I4, electrode ll, glow tube l8, vibrator l8 and electrode l2. This causes the vibrator [9 to vibrate and close the normally open switch I? whose contacts remain closed for a sufficient length of time that current flowing through the switch circuit will heat at least one of the filaments l l, l2. The vibrator then opens the switch I! and a voltage surge due to the inductance in the supply circuit, particularly from the transformer l5 and the ballast I3, is applied across the filaments ll, l2. This starts a continuous discharge in the tube In which maintains voltage drop across the filaments on the order of 108 volts which is insufficient to keep the glow tube l8 conducting. When the glow tube extinguishes breaking its circuit, the vibrator l9 stops vibrating and the switch l7 returns to and remains at its normally open position. If, for any reason, the voltage surge applied across filaments fails to initiate a steady discharge, the glow tube IE will continueto be conducting and the vibrator 59 will close and reopen the switch I! again. This operation will continue so long as the switch i6 is closed and the tube it fails to light.

If the vibrator i9 is of a type which may be damaged by a high voltage surge, such, for exam-- ple, as apiezoelectric crystal, a resistor 20 may the invention will be put in the vibrator circuit. This limits the voltage on the vibrator to a safe value.

The circuit of Figure 1 is utilized with a leading lamp and the circuit of Figure 2 is used with a lagging lamp. .The circuits are practically the same except that for thelagging lamp the condenser i4 is omitted, but the operation of the two circuits is substantially identical.

The circuit for the lagging lamp includes a condenser II of from about .05 to .5 microfarad connected across the filaments H, II in parallel with the switch This tunes the inductor I! at a frequency which is high with respect to the line frequency, for example 600 cycles per second if line frequency is about 60 cycles per second, thereby increasing the voltage of the surge and improving the starting characteristics of the lagging lamp to an extent such that start then the leading lamp.

The contacts of the switch l1 carry most of the current which passes through the filaments and should be made of silver or tungsten to prevent sticking, and the contact break apart should be done quickly to reduce arcing and to increase the voltage of the surge across the filaments II, II. The vibrator and switch shown in detail in Figure 5 and described later is designed to maintain the contacts of switch l1 closed sufficiently long to obtain proper filament heating and to then quickly open the contacts to get a quick substantially sparkless contact break.

Figure 3 illustrates a circuit for use with a leading lamp. An advantage in this circuit is that the switch I1 is normally closed. Accordingly, practically instantaneously with the closing of switch l6 the lamp filament means begin to heat and by the time the vibrator l9 vibrates with sufllcient amplitude to break the contacts of switch [1 apart the filament temperature has risen, and upon the voltage surge being applied across the filaments the lamp will light and maintain the discharge. In this circuit a condenser 25 is connected across the vibrator i9 and in series with the switch l1 and glow tube l8 for providing sufficient voltage to operate the vibrator and to limit the flow of current through the glow tube l8 to a value which will not destroy the glow tube l8. This circuit depends primarily upon a high voltage surge to light the lamp but the slight heating of the filaments is beneficial.

Figure 4 illustrates a circuit somewhat like the circuit of Figure 3 but adapted for a lagging lamp. The condenser ll of Figure 3 is not utilized and a condenser 2| is connected across the filaments II, I: for tuning the inductor Hi to a frequency high with respect to the line frequency, as has been explained in connection with Figure 2.

Figure 5 illustrates the details of a switch for a lamp starting circuit of the type shown in Figure 3 wherein the switch i1 is normally closed.

A piezoelectric crystal element 34 of the multiplate fiexing type is mounted on a base 60 by means of mounting pads 40. A detailed description of the multiple fiexing element may be had by referring to Sawyer, Re. 20,213 and Re. 20,680. The element preferably is of the twister type and is connected at three of its four corners of the base 60. If a bender" crystal is used it may be preferable to use a somewhat oblong or trapezoidal shaped crystal instead of the square shape which is preferred in the twister crystal. A drive rod H is connected to the fourth or vibratile corner of the crystal 34 and is in driving engagement with an intermediate portion of the it is easier to spring contact arm 6|. One end of the arm ii is connected to the base it by the support 65 and the other end carries a contact 43. Thus the contact 43 will move with greater amplitude than the vibratile portion of the crystal 34. A second spring contact arm 62 carries a contact ll which is positioned immediately above and in engagement with the contact 43. The arm 62 is connected at one end of the drive rod ll and the other or free end 83 which extends beyond the contact 48 is positioned near a stop 64. The leads SI, 52 are connected, respectively, to the spring arms BI, 62 and the free endsof the leads are adapted.to be connected to the lamp electrodes. In operation when the crystal 34 vibrates in accordance with an alternating signal between the leads 5, 55 both of the contact arms are vibrated. The upper spring system. which preferably has a resonant frequency equal to or greater than the resonant frequency of the lower spring system, follows the lower system thereby keeping the contacts 43, ll in engagement with each other. During this time interval the current flowing through the contacts heats the lamp filamen H, II. When the amplitude of motion of the two contacts 43, 48 builds up sufficiently the arm extension 63 strikes the stop 64 thereby quickly breaking the contact engagement to establish the required voltage surge. If the lamp fails to light, thecontacts ll, 48 will reengage for a fraction of a second and will then break apart again. This operation will continue until the lamp lights.

In operation the crystal element 34 vibrates at the line frequency, say 60 cycles per second, and the element preferably has a resonant frequency at or close to the line frequency so that maximum amplitude of motion of the drive wire 4| is obtained.

The best time to break the circuit is when the voltage across the filaments is near its maximum and when the current is also neariits maximum. However, even then the voltage surge due to breaking the current might be negative with respect to the voltage across the filaments, resulting in a low voltage surge. This is an added reason for increasing the rapidity at which the switch contacts break in order to obtain a contact break when the voltage due to breaking the current is high and of the same polarity as the voltage across the filaments which should be near its maximum.

For the lagging lamp, a condenser H is connected across the lamp filaments tuning the choke l3 to a frequency which is high compared to the line frequency, say, for example, 600 cycles per second. This increases the probability of the lagging lamp starting as it establishes a large number of voltage surges in each cycle as the circuit is broken. These voltage surges are added to the voltages due to breaking the current and to the voltage across the lamp, resulting in an extremely high surge if the circuit conditions are such that they are all near their maximum in one direction. If the circuit conditions are not ideal upon the first break but the switch makes and breaks rapidly, perhaps 60 times per second, then a break will soon occur when-the circuit conditions are good enough to ignite the lamp.

While we have described our invention with a certain degree of particularity it is to be understood that the illustrated means are by way of example, and that changes may be made in the construction and arrangement of parts without departing from the spirit and scope of our invention.

We claim as our invention:

1. A starting relay comprising, in combination. a base. a first spring arm connected at one of its ends to said base, first electrical contact means connected to said first arm at a location spaced from said connected end. the 'said first arm and said first electrical contact means constituting a first spring system having a given resonant frequency, electromechanical transducer means connected to said base; a second spring arm connected at one or its ends to said electromechanical transducer and adapted to be driven thereby, second electrical contact means connected to said second arm and normally in electrical engagement with said first electrical contact means, said second arm and said second electrical contact means constituting a second spring system having a resonant frequency greater than the resonant frequency of said first spring system, driving means connecting said transducer to said first spring system, and means for limiting the amplitude of motion of one 01 said spring systems without limiting the ampli-- tude of motion of the other spring system.

2. The invention set forth in claim 1 further characterized by said amplitude limiting means limiting the amplitude 01' motion of said second spring system.

3. The invention set forth in claim 1, further characterized by said driving means connecting said transducer to said first spring system at a point between said first contact means and the end or said first spring arm which is connected to said base.

HARRY B. SHAPER. CLIFFORD V. FRANKS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

